What is it? The air quality index pertaining to PM 2.5 (fine solid and liquid hazardous particles suspended in air) at RK Puram, a locality in Delhi, at 10pm on Tuesday, according to the US Embassy.

Why is it important? This falls in the “hazardous" category, the worst among six. By comparison, a score between 0 and 50 qualifies as “good", while 51-100 translates to “moderate". The Indian Medical Association said the national capital was witnessing a public health emergency and warned people against stepping out. The National Green Tribunal pulled up the governments of Delhi, Haryana and Uttar Pradesh, and asked them why steps were not taken to prevent deterioration in air quality.

Tell me more: The Environment Pollution Control Authority has recommended the following measures: parking fees in Delhi-NCR region be quadrupled, Delhi Metro reduce fares during off-peak hours for at least 10 days and introduce more coaches, road construction agencies violating pollution norms be fined Rs50,000, and the Delhi government start preparing for measures such as the odd-even scheme and ban on construction activities.

17.6%

What is it? The increase in e-returns filed until October in 2017-18 (37.8 million), up from 32.2 million filed in the corresponding period in 2016-17.

Why is it important? Today marks a year since the shock announcement of withdrawal of high-value currency notes, which the government defended as part of its efforts against black money and corruption. The increase in e-returns is one of the data points released by the government to demonstrate impact. Other data points include a widening of the tax base, amount deposited and withdrawn by companies, and striking off of firms from the Registrar of Companies and disqualification of directors.

Tell me more: The number of individual e-filers (who use form ITR-1) increased by 23.3% to 20.8 million between April and October this year, from 16.9 million.

0.2%

What is it? The percentage of passengers per 10,000 who filed complaints against IndiGo in September, according to the airline regulator. Among major domestic airlines, this is the lowest.

Why is it important? On Tuesday, India’s largest airline came under flak when an IndiGo staffer was seen manhandling a passenger. IndiGo has since suspended the staffer and its chief executive officer Aditya Ghosh has tendered an apology. Earlier in the week, Indian badminton player P.V. Sindhu had accused the airline’s staff of rude behaviour, which the airline contested.

Tell me more: Among domestic airlines, Air India had the highest complaint rate (1.6% per 10,000 passengers carried), followed by Jet Airways and JetLite (1.3%).

$1.5 billion

What is it? The loss posted by Denmark’s AP Moller Maersk in the July-September quarter, against a profit of $429 million in the corresponding year-ago period, despite an increase in revenues from $7 billion to $8 billion.

Why is it important? The world’s largest shipping company, also an oil producer, has partly attributed this loss to the cost of a cyber-attack in June—of $250-300 million—that primarily affected its shipping unit. This makes a persuasive case for businesses to bolster their IT systems to thwart cyber attacks.

Tell me more: According to a recent report by Lloyd’s of London, a major, global cyber attack could cause economic losses to the tune of $53 billion, which would be equivalent to the losses due to a catastrophic natural disaster such as the US super-storm Sandy in 2012.

1-1

What is it? The head-to-head record between Indian badminton players P.V. Sindhu and Saina Nehwal in the international sphere.

Why is it important? The two women, who put India on the world badminton map, on Tuesday reached the finals of the Senior Badminton National Championship. This summit clash will be a rare encounter between the two who are referred to in a similar vein but whose tenures at the very top have coincided little.

Tell me more: Nehwal won the first international encounter in January 2014, while Sindhu won in March 2017. Saina is 27, while Sindhu is 22.